The PRESIDENT'S latest economic plan is the Carter administration at its best -- cautious, not very exciting, sensible. It speaks grandly of "revitalization" of American industry, but in this season terminology is apt to be a bit overinflated. The program itself will doubtless be greeted by a chorus of hoots and jeers from the people who wanted something hotter and stronger. But it's useful to remember that all of the hot, strong ideas on this subject currently are bad ones -- import restrictions, relaxations of environmental rules, broad inflationary tax cuts. The Carter program avoids large errors and sets off, in a gingerly way, in the right direction.

The central necessity, as the administration observers, is to find ways to stimulate investment and productivity without increasing the inflation rate. The first step is faster and simpler depreciation allowances for business, a traditional therapy but still the most efficient way toward faster investment. The administration goes beyond tradition with its next step, the investment credit that is refunded in cash. That's for the automobile and steel industries. Present law permits an investment credit against a business's income tax. But when a company makes no profit, it pays no income tax and the credit is useless. A refundable credit is a federal grant, or subsidy, paid regardless of the company's tax position and, as subsides go, it is not a bad concept. It is directly linked to investment and is infinitely preferable to loan gurantees managed out of the Treasury, in the style of the Chrysler rescue.

There's another interesting precedent in the proposal to offset the January increase in Social Security taxes with income tax credits -- for individuals, this time, as well as businesses. It means shifting some of the Social Security burden from payroll taxes to income taxes. That's right in principal and it also holds down inflation. Higher payroll taxes raise wage costs; income taxes do not.

In early January, talking with the automobile industry, Mr. Carter seemed to be on the verge of a dive into protectionism. Most of the unions are vehemently protectionist, and their idea of industrial revitalization began at the ports. Both candidates must be sorely tempted to respond. But Mr. Carter and, it should be said, Mr. Reagan have firmly resisted, so far, and both deserve credit for it.

Mr. Carter has also avoided the dangerous idea of trying the Japanese style of industrial planning -- which means playing economic favorities, with White House decisions to select certain industries for accelerated investment at the expense of others. Perhaps it work for Japan -- although there's some controversy about that. But in this country, with its very different style of politics, the benefits would undoubtedly be funneled to the losers and turn into artificial respiration for comatose companies. The strategies rejected are as important, in Mr. Carter's program, as the strategy chosen.

This economic plan is Mr. Carter's third, or perhaps fourth, since the beginning of the year. How seriously should this one be taken? It's an intelligent campaign document, a statement of intentions. It is a useful first draft for legislation to be presented next winter by another administration -- perhaps Mr. Carter's second, but perhaps not -- and passed by another Congress.